server: praphite error on log y axes

[pat1]

http://rmap.cc/graphite/render/?_salt=1550860945.992&logBase=10&vtitle=Humidity&from=-12hours&height=308&areaMode=stacked&showTarget=sample_fixed.dancast78.1137639_4449215.fixed.254_0_0.103_2000_-_-.B49192&yMin=0&width=586&vtitleRight=Temperature&lineMode=connected&target=sample_fixed.dancast78.1137639_4449215.fixed.254_0_0.103_2000_-_-.B49197&target=sample_fixed.dancast78.1137639_4449215.fixed.254_0_0.103_2000_-_-.B49196&target=sample_fixed.dancast78.1137639_4449215.fixed.254_0_0.103_2000_-_-.B49195&target=sample_fixed.dancast78.1137639_4449215.fixed.254_0_0.103_2000_-_-.B49194&target=sample_fixed.dancast78.1137639_4449215.fixed.254_0_0.103_2000_-_-.B49193&target=sample_fixed.dancast78.1137639_4449215.fixed.254_0_0.103_2000_-_-.B49192

GraphError at /graphite/render/
Logarithmic scale specified with a dataset with a minimum value less than or equal to zero
Request Method: GET
Request URL: http://rmap.cc/graphite/render/?_salt=1550860945.992&logBase=10&vtitle=Humidity&from=-12hours&height=308&areaMode=stacked&showTarget=sample_fixed.dancast78.1137639_4449215.fixed.254_0_0.103_2000_-_-.B49192&yMin=0&width=586&vtitleRight=Temperature&lineMode=connected&target=sample_fixed.dancast78.1137639_4449215.fixed.254_0_0.103_2000_-_-.B49197&target=sample_fixed.dancast78.1137639_4449215.fixed.254_0_0.103_2000_-_-.B49196&target=sample_fixed.dancast78.1137639_4449215.fixed.254_0_0.103_2000_-_-.B49195&target=sample_fixed.dancast78.1137639_4449215.fixed.254_0_0.103_2000_-_-.B49194&target=sample_fixed.dancast78.1137639_4449215.fixed.254_0_0.103_2000_-_-.B49193&target=sample_fixed.dancast78.1137639_4449215.fixed.254_0_0.103_2000_-_-.B49192
Django Version: 1.11.20
Exception Type: GraphError
Exception Value:
Logarithmic scale specified with a dataset with a minimum value less than or equal to zero
Exception Location: /usr/lib/python3.4/site-packages/graphite-dballe/render/glyph.py in chooseLimits, line 496
Python Executable: /usr/bin/python3
Python Version: 3.4.9

Traceback:

File "/usr/lib/python3.4/site-packages/django/core/handlers/exception.py" in inner
41. response = get_response(request)

File "/usr/lib/python3.4/site-packages/django/core/handlers/base.py" in _legacy_get_response
249. response = self._get_response(request)

File "/usr/lib/python3.4/site-packages/django/core/handlers/base.py" in _get_response
187. response = self.process_exception_by_middleware(e, request)

File "/usr/lib/python3.4/site-packages/django/core/handlers/base.py" in _get_response
185. response = wrapped_callback(request, *callback_args, **callback_kwargs)

File "/usr/lib/python3.4/site-packages/graphite-dballe/render/views.py" in renderView
144. response = renderViewGraph(graphOptions, requestOptions, data)

File "/usr/lib/python3.4/site-packages/graphite-dballe/render/views.py" in renderViewGraph
164. image = doImageRender(requestOptions['graphClass'], graphOptions)

File "/usr/lib/python3.4/site-packages/graphite-dballe/render/views.py" in doImageRender
576. img = graphClass(**graphOptions)

File "/usr/lib/python3.4/site-packages/graphite-dballe/render/glyph.py" in init
574. self.drawGraph(**params)

File "/usr/lib/python3.4/site-packages/graphite-dballe/render/glyph.py" in drawGraph
1090. self.setupYAxis()

File "/usr/lib/python3.4/site-packages/graphite-dballe/render/glyph.py" in setupYAxis
1470. yTics.chooseLimits()

File "/usr/lib/python3.4/site-packages/graphite-dballe/render/glyph.py" in chooseLimits
496. raise GraphError('Logarithmic scale specified with a dataset with a '

Exception Type: GraphError at /graphite/render/
Exception Value: Logarithmic scale specified with a dataset with a minimum value less than or equal to zero